Grinding Characteristics Research Articles

D015 Grinding characteristics of high-speed reciprocation profile grinding

D015 Grinding characteristics of high-speed reciprocation profile grinding

Influence of Grinding Atmosphere on Grinding Characteristics of CFRP (Effect of Soluble Coolant or Liquid Nitrogen Supply)

CFRP (Carbon Fiber Reinforced Plastics), which is increasingly applied to airplanes, automobiles, production equipment for electronic device, and so on, is machined after molding process. Grinding is often used for edge finishing of CFRP parts. This paper deals with the influence of grinding atmosphere on grinding characteristics of CFRP by the experimental investigation of ground surface characteristics, surface finish, grinding force, grinding temperature, etc. in surface grinding of unidirectional CFRP using a vitrified bond diamond wheel with the water soluble coolant and the liquid nitrogen in addition to dry grinding. The grinding temperature has been measured by a developed thermocouple system using carbon fibers being made up CFRP and a constantan wire setting between CFRP specimens. The grinding temperature at wheel contact area on CFRP is higher than the glass-transition temperature of CFRP at larger setting wheel depth of cut. The wet grinding prevents in worsening ground surface of CFRP and increasing grinding force that occur in dry grinding of CFRP. The liquid nitrogen makes some effect on prevention in wheel loading and delamination of carbon fibers in dry grinding of CFRP, however the grinding force supplying liquid nitrogen becomes larger than that in dry grinding because of an increase in hardness of CFRP by freeze up. The bending strength of ground CFRP, which suggests the scale of affected layer, is improved by supplying the water soluble coolant and the liquid nitrogen in grinding process.

Hybrid micromachining of glass using ECDM and micro grinding

Micro electrochemical discharge machining (ECDM) is a well-known machining process that achieves 3D micro structures in glasstype material. However, a rough surface is the main disadvantage of this process. In the present work, a hybrid process of ECDM and micro grinding using polycrystalline diamond (PCD)tools is investigated. Micro structures in glass workpieces were machined by ECDM and then ground by PCD tools to improve the surface quality. Micro grinding by PCD tools is used to overcome the rough surfaces that are generated by sparks in ECDM. The characteristics of micro grinding, such as the surface roughness of the tool, depth of cut, and feedrate, using PCD tools for ECDM structures were investigated. It is experimentally shown that the grinding process under PCD tools reduces the surface roughness of ECDM structures from a few tens of a μm to 0.05 μm Ra, and the total machining time of the hybrid process is less than a third compared to that under a conventional grinding process.

Preliminary Study on Mechanism of Superalloy Deep-Hole Honing Technology

Anglicizing the superalloy mechanical and cutting characteristics, and according to the oil-stone grinding characteristics, choose the current commonly abrasives in the domestic. Processing performance test of inconel 718 deep-hole honing is carried out. The comparison test results show that the grinding performance of ceramic corundum is better than other oilstones at test condition. Grinding characteristics of ceramic corundum is carried on, study show that the size of ceramic alumina grits range from 0.067 to 0.005 μm, The grinding passivated tiny grains of ceramic corundum oil-stone broken and fall off timely, which is beneficial to oil-stones, self-sharpness. The excellent performance of ceramic corundumcan self-sharpening can improves the efficiency of honing effectively.

Precision Grinding Characteristics and Process Optimization on YG3 Cemented Carbide

Precision grinding experiment and process optimization of YG3 cemented carbide materials was conducted with various grinding parameters using resin-bonded diamond grinding wheel. Different rotation speed of workpiece, feed rate and grinding depth were chozen in precision cross grinding. Surface roughness was measured for studying the removal mode and grinding charateristics. A set of ideal grinding parameters of YG3 cemented carbide were obtained by changing the process parameters. The research result has guiding significance for reducing the wheel wear and processing costs, improving grinding quality and efficiency while precision grinding hard and brittle materials.

분쇄 방법이 품종이 다른 쌀가루의 품질에 미치는 영향

국내에서 육종된 8가지 품종의 쌀을 습식과 건식제분하여 제분 방법에 따른 쌀가루의 품질변화를 품종별로 분석하고 이를 바탕으로 제분 방법에 비교적 민감하지 않고 일정한 품질의 가루를 생산할 수 있는 국내산 쌀 품종을 찾고자 하였다. 건식제분은 예상한 바와 같이 낟알의 경도가 높은 품종이 전분 손상도가 높았으나 습식제분에서는 Chenmaai와 같이 불린 쌀의 경도가 높더라도 전분의 손상도는 상대적으로 낮았다. 건식제분에 따른 손상 전분 함량의 증가는 쌀가루의 수분 흡수력을 급격히 증가시켰으며 습식제분은 낟알의 경도보다는 아밀로오스 함량에 따라서 수분 흡수력에 차이를 나타내었다. 가루의 수분 흡수력과 반비례하여 반죽의 질척한 정도가 나타나지만 고 아밀로오스 함량의 Suweon 517과 Milyang261은 제분 방법에 관계없이 수분 흡수력이 매우 높아서 빵이나 국수 등의 제품을 생산할 때 반죽에 더 많은 양의 물을 첨가해야 할 것으로 생각된다. 또한 건식제분된 가루가 습식제분된 가루에 비하여 수분 흡수력이 크기 때문에 반죽 과정에서 수분 첨가량을 증가시켜야 할 것이다. 건식제분은 품종 모두에서 최고 점도에 이르는 시간이 짧아지고 점도 붕괴가 증가하므로 습식 가루에 비하여 조리시간을 단축하고 호화 후 점도 조절이 필요하다. Hanareumbyeo, Manmibyeo, J insumi , Goamibyeo 등은 건식제분과 습식제분에 따른 호화 특성의 변화가 다른 품종에 비하여 크며, Suweon517과 Milyang261은 건식제분하면 setback 값이 증가하는 것으로 미루어 건식제분된 가루를 이용한 제품의 노화가 더 클 것으로 예측된다. 이상의 결과에 따라서 Chenmaai는 건식과 습식제분 모두에서 손상 전분의 함량이 낮고, 건식제분에 따른 수분 흡수율 증가가 적으며 제분에 따른 호화 점도 특성의 변화가 상대적으로 적어서 제분에 유리한 품종이다. 반면 Seolgaeng와 Suweon517은 낟알의 경도가 부드러운 분상질일지라도 건식과 습식제분 모두에서 손상전분 함량이 높고 수분 흡수력과 호화 점도의 특성 변화가 심하여 쌀가루로 분쇄하는 제분 적성이 좋지 않았다.

Grinding Characteristics and Mechanism of Ceramic Alumina Wheels on Aeronautical Alloys

The present investigation was dedicated to elucidate grinding characteristics during surface grinding of titanium alloy(TC6) and high temperature alloy (GH2132) by using silicon carbide(SiC) and sol-gel (SG) wheel respectively. The grinding characteristic of SG wheel on aeronautical alloys was studied on the base of systematical measurement of the grinding force, grinding temperature, surface roughness and grinding ratio. The results indicated that the SG grinding wheel possesses excellent grinding properties and is more suitable for grinding these aeronautical alloys compared with conventional abrasive tools. Finally, the grinding mechanism of new-typed SG wheel was unveiled on the base of the microcrystalline structure analysis of SG grains.

Application of Nano Cutting Fluid under Minimum Quantity Lubrication (MQL) Technique to Improve Grinding of Ti – 6Al – 4V Alloy

Minimum Quantity Lubrication (MQL) technique obtained a significant attention in machining processes to reduce environmental loads caused by usage of conventional cutting fluids. Recently nanofluids are finding an extensive application in the field of mechanical engineering because of their superior lubrication and heat dissipation characteristics. This paper investigates the use of a nanofluid under MQL mode to improve grinding characteristics of Ti-6Al-4V alloy. Taguchi’s experimental design technique has been used in the present investigation and a second order model has been established to predict grinding forces and surface roughness. Different concentrations of water based Al2O3 nanofluids were applied in the grinding operation through MQL setup developed in house and the results have been compared with those of conventional coolant and pure water. Experimental results showed that grinding forces reduced significantly when nano cutting fluid was used even at low concentration of the nano particles and surface finish has been found to improve with higher concentration of the nano particles. Keywords—MQL, Nanofluid, Taguchi method, Ti-6Al-4V.

Investigation of grinding characteristic using nanofluid minimum quantity lubrication

Conventional grinding fluid is widely used in grinding process, which results in high consumption and impacting the environment. The promising alternative to conventional dry and fluid coolant application is minimum quantity lubrication (MQL). It is known that the cooling and lubrication performance of the grinding fluid is the key technical area for the success application of MQL grinding process. In this study, Water based Al2O3 nanofluid was applied to grinding process with MQL approach for its excellent convection heat transfer and thermal conductivity properties. The grinding characteristics of hardened AISI 52100 steel were investigated and compared with those of wet, dry and pure water MQL grinding. Experimental results show that water based Al2O3 nanofluid MQL grinding can significantly reduce the grinding temperature, decrease the grinding forces, improve the ground surface morphology and reduce the surface roughness in comparison to pure water MQL grinding. Furthermore, the cooling and lubricating mechanism for nanofluid MQL grinding was discussed in detail.

Phase transformation in high-speed cylindrical grinding of SiC and its effects on residual stresses

Recently, the polytype transformation of SiC has been studied at temperatures over 2000K or at high pressures. However, there are no theoretical or experimental works exploring phase transformation during grinding process of SiC to date. In this work, the grinding characteristics such as temperature rise, high dynamic pressure and shock effect are compared with conditions for phase transition. For the first time, X-ray diffraction analysis of ground SiC under different machining conditions reveals that phase transition in high-speed cylindrical grinding occurs and strongly affects the residual stresses on the surface layer. Furthermore, a way to reduce the residual stresses by a combination of the elevated grinding wheel velocity and the higher workpiece speed is proposed.

The Characteristics of High-Speed Cylindrical Grinding of Silicon Carbide and its Influence on the Surface Layer

There has been increased interest in the use of advanced ceramic materials such as silicon carbide in the recent past, due to its unique physical and mechanical properties. However, the increase of the machining rate relies on the understanding of material removal mechanism on the microstructural scale and the relationship between the grinding characteristics and formation of surface/subsurface machining-induced damage. In this paper, grinding characteristics and surface integrity of SiC ground with diamond wheel on cylindrical grinding machine have been investigated. The grinding chip and the ground surface damage have been studied with scanning electron microscope (SEM). In particular the residual stress distribution has been analyzed by a single exposure technique d - sin2 (Ψ) method with the aid of powder X-ray diffractometer.

高速超音波スピンドルによる硬脆材料の精密・微細研削に関する研究（第3報）

高速超音波スピンドルによる硬脆材料の精密・微細研削に関する研究（第3報）

Grinding performance of wheat, maize and soybeans in a multicracker system

This manuscript presents the effects of a recent technology for particle size reduction using a new approach in which the cracking action of two rows of discs is used. Wheat, maize and full fat soybeans were ground by a multicracker system to study the effects of disc type (ceramic versus steel discs), disc speed in revolutions per minute (2650 versus 3800rpm), throughput (3.43 versus 6.70metric t/h) and the gap between the discs (0.11 versus 1.04mm). Mean particle size, width of the particle size distribution curve and total and specific mechanical energy consumption were the dependent variables under investigation.Maize, soybeans and wheat had different grinding characteristics (P<0.001) in the multicracker system with mean particles sizes of 1.76, 2.10 and 2.08mm, respectively; the width of the particle size distribution, however, being not different for the different seeds. The mean particle size of the initial whole ingredient divided by the mean particle size of the ground samples, referred to as the reduction ratio differed largely (P<0.001) between the seeds. For maize, soybeans or wheat the reduction ratio was 4.53, 2.76 and 1.71, respectively. All particle characteristics of the ground ingredients (mean particle size, width of the particle size distribution and reduction ratio) were not affected by the capacity of the installation in the range of 3.43–6.70t/h. Soybeans showed the highest specific mechanical energy (2.8kWh/t) at the highest mean particle size compared to maize and wheat (2.1 and 1.8kWh/t, respectively).Disc type was examined to be an important variable that largely affects (P<0.001) all particle characteristics as well as the consumption of specific mechanical energy, steel discs revealing the lowest energy requirements.

Multiple-response optimisation of electrochemical grinding characteristics through response surface methodology

This paper comprehensively evaluates the influence of voltage and cutting speed on electrochemical grinding of composite carbide inserts. A complete 42 factorial experiment was planned and carried out where each treatment combination has been replicated twice to achieve an acceptable degree of precision. Mathematical models have been developed for the major performance indices like current density, material removal rate (MRR) and surface finish of the job by multiple linear regression analysis. Then multiple-response optimisation has been carried out to find the optimum parameter settings to get a desired yield both by desirability functions as well as by contour overlapping method. It has been found that passivation occurs increasingly at higher voltages and it is removed almost instantaneously at higher speed leading to higher current density and MRR. The surface finish is not very much dependent on grinding speed. The optimum surface finish is obtainable at 12 to 13 V (app.) in electrochemical grinding of composite carbides.

高速超音波スピンドルによる硬脆材料の精密・微細研削に関する研究（第2報）

高速超音波スピンドルによる硬脆材料の精密・微細研削に関する研究（第2報）

Dressing and truing of hybrid bonded CBN grinding tools using a short-pulsed fibre laser

This paper presents the results of an investigation into the dressing and truing of hybrid bonded (metal-vitrified) CBN grinding wheels using a short-pulsed fibre laser. Truing of complex contours on CBN grinding tools with sharp edges (edge radii of less than 20μm) could be successfully applied, whereas other dressing methods have been neither technically nor economically successful. Sharpening by laser can provide the same wheel surface topography which is conventionally produced by SiC and/or Al2O3 sharpening tools. Grinding characteristics and long-term performance of the laser-profiled tools are discussed.

Characterization and Use of Egyptian Nubian Sandstone in the Ceramic Tile Industry

Egyptian ball clay quarried in the Aswan area in Upper Egypt contains up to 10% Nubian sandstone. This inclusion causes problems in clay grinding when used in ceramic industries. In the present paper, Nubian sandstone was characterized for mineralogical and chemical compositions using XRD and XRF respectively. Its grinding characteristics were then established using a laboratory ball mill where stone was ground for time periods ranging from 60 to 150 min at speeds ranging from 40 to 90 rpm. The cumulative analysis and specific surface area were determined for all samples. It was found that while an increase in either time or speed favoured higher fineness, the effect of rotating speed was more pronounced than that of grinding time. The findings were then applied to the production of ceramic tiles. It was found that crushed sandstone could be crushed and ground with ball clay without impairing the grinding characteristics of the latter or affecting the composition of the final body.

Research on Improving the Classification-Gravity Concentration Technology Based on an Anshan-Type Low-Grade Hematite Ore

The beneficiation of Anshan-type low-grade hematite ores attracts more and more attention. Complicated beneficiation flow sheets are necessary to deal this type of ores. Classification-gravity concentration technology is used widely in these flow sheets because of its characteristics. In this paper, grinding characteristics and classification-gravity concentration tests were carried out based on the ore’s mineralogical characteristics. When the ground size of the ore was 75% -0.071mm, through beneficiation by the flow sheet of classification-gravity concentration-middle intensity magnetic separation discarding, a satisfactory concentrate assaying 67.58% Fe, 47.51% recovery was obtained, and the iron grade and yield of the tailings were 5.93% and 39.77% respectively. The controlling of the size distribution and the behavior of finer hematite grains is important and efficiency in beneficiation of Anshan-type hematite ores.

508 葦カーボンを用いた砥石の開発と加工特性(OS7-3 オーガナイズドセッション《精密/微細加工と評価》)

508 葦カーボンを用いた砥石の開発と加工特性(OS7-3 オーガナイズドセッション《精密/微細加工と評価》)

Review of Quick-Point Grinding Technology

Quick-point grinding technology, suitable to be applied in automobile manufacturing, cemented carbide and ceramic material processing industry, was an advanced ultra-high-speed grinding technology. It is the integration of super-high speed grinding, CBN super-abrasive and CNC flexible manufacturing and so on. The characteristics of quick-point grinding were systematically illustrated. Applications of this technology to process hard-machining materials and shaft parts were also given in this paper. Some problems and solutions corresponding to quick-point grinding technology were presented finally.